1. Field of the Invention
The present invention relates to a method of forming spacers onto substrates constructing an electron-beam light-emitting display panel.
2. Description of the Related Art
A method of forming a spacer for a plasma display panel onto substrates by using two or more compositions in which solubilities to a developing solution are different has been known in the related art (for example, refer to Patent Document 1). That is, there has been known a method whereby the compositions are laminated from the substrate side so that the solubility to the same developing solution decreases sequentially, a resist pattern is formed onto the laminated layer, thereafter, a developing process is executed by using the developing solution which is common for each layer, and the pattern of the laminated layer thus obtained is baked, thereby forming the spacer. According to the above method, such a phenomenon that an upper layer which is come into contact with the developing solution for a time longer than that for a lower layer is excessively side-etched and its front edge becomes a thin shape can be prevented and the spacer having a large aspect ratio can be formed.
A method whereby a spacer which has concave/convex portions on a side surface and is used for an electron-beam light-emitting display panel is manufactured by casting has also been known (for example, refer to Patent Document 2). By forming the concave/convex portions onto the side surface of the spacer, a creepage distance is extended and a charge due to a secondary electron emission is suppressed, thereby enabling a creepage discharge to be easily prevented.    [Patent Document 1] Official Gazette of Japanese Patent Application Laid-Open No. 2004-127949    [Patent Document 2] Official Gazette of Japanese Patent Application Laid-Open No. 2000-243274
However, according to the method disclosed in Patent Document 1 mentioned above, for example, as shown in Paragraph [0025] of Patent Document 1, it is fundamentally intended to obtain the spacer with a cross sectional structure having the side surface that is perpendicular to the substrate and it is never intended to apply the concave/convex shape to the side surface of the spacer.
On the other hand, in the case of forming the concave/convex shape to the spacer for the electron-beam light-emitting display panel, if the sharp-cornered concave/convex shape is formed and, particularly, a lower surface of the convex portion is projected almost in parallel with a substrate surface, it is liable to suppress an emission of a secondary electron accompanied with an incidence of an electron. The creepage distance can be extended longer than that in the case where the lower surface of the convex portion is gently inclined.
However, the concave/convex portions which are formed onto the spacer for the electron-beam light-emitting display panel are the microfine portions and according to the casting disclosed in Patent Document 2, there is such a problem that the sharp-cornered concave/convex shape cannot be formed because of a limitation of die reproducibility. Specifically speaking, as illustrated in FIG. 3 of Patent Document 2, the concave/convex portions which are formed run wavily. There is, consequently, such a problem that an emission suppressing effect of the secondary electron and an increasing effect of the creepage distance are inferior to those in the case of forming the sharp-cornered concave/convex portions.